Menu desalinhado

import java.awt.*;
import javax.swing.*;

public class AplicacaoPoupanca4 extends JFrame{

    private JTextField campoJuros, campoAnos, campoDeposito;
    private JLabel lbJuros, lbAnos, lbDeposito, lbTotal, lbResultado;
    private JButton ok;
    private JMenu menu;
    private JMenuBar barraMenu;
    private JMenuItem menuItem;

     public AplicacaoPoupanca4(){

        super("Poupex");

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.setBounds(50,100,400,200);


        JPanel painel = new JPanel();

        painel.setLayout(new GridLayout(6,2));
        this.getContentPane().add(painel);

        barraMenu = new JMenuBar();
        menu = new JMenu("Arquivo");
        menuItem = new JMenuItem();

        barraMenu.add(menu);
        
        painel.add(barraMenu);





        JPanel painel10 = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel painel11 = new JPanel();

        lbJuros = new JLabel("Juros ao mês %:");
        campoJuros = new JTextField(15);

        painel10.add(lbJuros);
        painel11.add(campoJuros);

        painel.add(painel10);
        painel.add(painel11);

        JPanel painel12 = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel painel13 = new JPanel();

        lbAnos = new JLabel("Num. de anos:");
        campoAnos = new JTextField(15);

        painel12.add(lbAnos);
        painel13.add(campoAnos);

        painel.add(painel12);
        painel.add(painel13);

        JPanel painel14 = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel painel15 = new JPanel();

        lbDeposito = new JLabel("Depósito mensal R$:");
        campoDeposito = new JTextField(15);

        painel14.add(lbDeposito);
        painel15.add(campoDeposito);

        painel.add(painel14);
        painel.add(painel15);

        JPanel painel16 = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel painel17 = new JPanel();

        lbTotal = new JLabel("  Total poupado R$:");

        painel.add(lbTotal);

        painel.add(painel16);
        painel.add(painel17);

        JPanel painel18 = new JPanel(new FlowLayout(FlowLayout.LEFT));

        ok = new JButton("OK");

        painel18.add(ok);

        painel.add(painel18);
     }
}

public class Main

{
    public static void main(String args[]) {

        AplicacaoPoupanca4 janela4 = new AplicacaoPoupanca4();
        janela4.setVisible(true);
    }
}